Investigation of the Preventive Effects and Safety of Increasing Antimicrobial Agent Dose in Patients Who Are Overweight and Undergoing Orthopedic Surgery for Surgical Site Infection

The practice guidelines for the appropriate use of prophylactic antibiotics for postoperative infection prevention recommend cefazolin (CEZ) for preventing surgical site infections (SSI) during orthopedic surgeries. For patients who are overweight/obese, an increased single dose of 2 g is recommended. Therefore, we selected patients weighing 80 kg or more who underwent surgery at our orthopedic surgery; then, we conducted a retrospective study of the preventive effect and safety of increasing antimicrobial agent dose, using the standard group (1 g per dose) from June 2018 to May 2021 and the increased group (2 g per dose) from June 2021 to May 2023. The standard group included 66 patients, whereas the increased group included 55 patients. SSI occurred in two patients in the standard group and zero patients in the increased group, with no significant difference between the groups (P = 0.295). The postoperative hospital stays were 11 days in the standard group and 12 days in the increased group (P = 0.938). Clinical laboratory values (ALB, ALT, Hb, and PLT) showed significant changes before and after surgery; however, no adverse events were observed owing to the increased CEZ dosage. The two patients who developed SSI in the standard group were relatively young and had good renal function, suggesting that the 1 g dose may not have reached an effective blood concentration commensurate with the increased distribution volume in patients who are overweight; therefore, dosage escalation should be considered for these patients. If the dosage is not increased, careful monitoring for postoperative infections is essential.